Field of the Invention
The invention relates to a washing tub for a washing machine, having a rear wall made from injection-molded plastic and a laundry drum mounted at least substantially horizontally and connected in a manner fixed in rotation to a shaft mounted in the rear wall and driven through a drive mechanism.
German Utility Model DE 92 15 811 U1, corresponding to U.S. Pat. No. 5,329,791 to Cargnel, discloses such a conventional washing tub made entirely of plastic and, thus, also includes a rear wall made from plastic. The rear wall has ribs, preferably extending radially, which increase the strength of the washing tub. A radial ring is also present to achieve greater strength, the radial ring extending concentrically with a central hub. Supported in the hub through bearings is a drive shaft that bears the laundry drum. The shaft is disposed horizontally and is driven through a drive mechanism.
British Patent No. GB 2 333 300 A and European Patent Application EP 0 219 115 A2 likewise disclose a washing tub made from plastic for a washing machine.
German Published, Non-Prosecuted Patent Application DE 197 24 930 A1, corresponding to U.S. Pat. No. 6,050,115 to Skrippek et al., discloses a washing machine having a drive mechanism whereby the laundry drum is driven directly. The motor includes a stator connected to the base wall of the washing tub. The rotor is disposed at the end on the shaft of the laundry drum.
It is accordingly an object of the invention to provide a washing tub for a washing machine that overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and that improves a washing tub by compactly constructing the drive mechanism.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a washing tub for a washing machine, including a plastic injection-molded rear wall, a shaft mounted in the rear wall, an at least substantially horizontally mounted laundry drum connected to the shaft in a rotationally fixed manner, a drive mechanism connected to the drum for driving the drum, the drive mechanism having a stator support part, and the rear wall plastic injected molded around the stator support part and rotationally fixing the stator support part thereto.
The stator support part of the drive mechanism is, preferably, of metal; in particular, it is a gray iron casting or an aluminum casting. It can be placed in a plastics injection-molding device such that plastic can be injected around it. As a result, a simple positive-fitting or non-positive-fitting connection with the plastics part can be achieved. The plastics part may be the rear wall of a washing tub, a part of the washing tub encompassing the rear wall, or the washing tub as a whole.
In accordance with another feature of the invention, the stator support part is connected through its surface to the plastic by positive or non-positive fitting. For such a purpose, the stator support part includes, on the side facing the plastics rear wall projections, lugs, notches or recesses into which the plastic is injected or around which the plastic is injected, as the case may be, so that a positive-fitting connection between the stator support part and the rear wall is achieved. Alternatively, the stator support part includes a surface that, for example, has sufficient roughness to create an adequately non-positive-fitting connection between the metal of the stator support part and the plastic of the rear wall.
Preferably, the stator support part is disposed centrally around the drive shaft and includes stator packs disposed concentrically with the drive shaft, if a direct drive for the laundry drum is provided. Alternatively, a stator support part may also be disposed eccentrically relative to the drive shaft on the rear wall of the washing tub if a transmission or a drive belt in conjunction with pulleys is disposed on the rear wall of the washing tub to transmit the rotational movement of the drive mechanism to the drive shaft. Such a drive mechanism for the indirect drive, which is fixed on the rear wall of the washing tub, is disclosed in German Published, Non-Prosecuted Patent Application DE 199 11 139 A1.
As a result of the configuration according to the invention of the rear wall of the washing tub, a simple bearing for the stator support part of the drive mechanism is provided, the stator support part simultaneously increasing, because of its shape, the strength of the rear wall. Preferably, the stator support part is also surrounded by an annular wall, which interacts with a reinforcing rib of the rear wall. The rear wall preferably includes an angled web that at least partially encloses the annular wall portion of the stator support part.
In accordance with a further feature of the invention, the rear wall has a base wall and a reinforcing ring and the stator support part is connected to the base wall and to the reinforcing ring.
In accordance with an added feature of the invention, the reinforcing ring has a collar enclosing the stator support part.
In accordance with an additional feature of the invention, the drive mechanism has a bearing sleeve and the stator support part encloses the bearing sleeve.
In accordance with yet another feature of the invention, the stator support part forms a bearing sleeve for receiving bearings through which the shaft 5 is mounted to the rear wall 3.
In accordance with yet a further feature of the invention, the drive mechanism has a bearing sleeve and the bearing sleeve has a plastic shell.
In accordance with yet an added feature of the invention, the plastic shell is a reinforcing ring.
In accordance with yet an additional feature of the invention, the stator support part has rings concentric with the shaft.
In accordance with a concomitant feature of the invention, the rear wall has a base wall with a convexity concentric with the shaft and enclosed by the stator support part. The rear wall includes at least one annular convexity, which is enclosed by a wall portion of the stator support part so that a large connecting surface is formed between the rear wall and the stator support part and a high non-positive fit comes about between the two. The connection between the rear wall and the stator support part in this case is additionally supported by convexities or projections that are not symmetrical in rotation about the axis of the drive shaft.
The invention can be used both with a horizontally mounted laundry drum and with a laundry drum mounted at an angle, in which case the laundry drum is mounted, for example, at 15xc2x0 relative to the horizontal.
As a result of the configuration according to the invention, the drive mechanism has a compact structural form and can simultaneously be connected in a simple manner to the rear wall.
Other features that are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a washing tub for a washing machine, it is, nevertheless, not intended to be limited to the details shown because various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.